1. Field of the Invention
This invention relates to a catheter for use in introducing an aerated stream of liquid into a body cavity. More specifically, this invention relates to a catheter of particular utility in ultrasonic hysterosalpingography.
2. Description of the Related Art
The use of air bubbles as an echogenic medium is known. A liquid is temporarily aerated by shaking vigorously. The aerated liquid is introduced through a catheter into a cavity in the body to enhance the ultrasound opacity of the cavity. The aerated liquid is subsequently visualized with ultrasound, transiently outlining the cavity into which it is injected.
Heretofore, the aerated solution, i.e., the mixture of air and water, was made at the proximal end of the catheter or in a syringe inserted into the proximal end of the catheter. Thus, the aerated solution had to travel the length of the catheter to the distal end portion for delivery into the cavity. This resulted in the bubbles coalescing and/or dissolving by the time they reached the cavity. Consequently, this technique did not enable a steady stream of small bubbles to be consistently produced, thereby inhibiting ultrasound induced visualization of the cavity.
Moreover, the prior art method of introducing aerated solutions at the proximal end was limited in that controlled stopping and starting could not be achieved since the solution was injected from a position remote from the distal end. Thus, placement of small, controllable amounts of air bubbles at specific locations could not be obtained effectively.
To one application in which an aerated solutions may be used for ultrasound visualization is hysterosalpingography (HSG), a diagnostic procedure for analyzing the uterus and fallopian tubes to determine if they are complete or if there are any blockages which are causing infertility. Hysterosalpingography is commonly performed by injecting radiopaque dye into the fallopian tube and then using fluoroscopic examination for visualization. However, this exposes the patient to ionizing radiation which might detrimentally effect the patient's health. Additionally, it increases the cost of the procedure because a radiologist is required.
Accordingly, a principal object of the invention is to provide a catheter construction capable of infusing an aerated stream of liquid into a body cavity for ultrasonic visualization, particularly for hysterosalpingography.
A more specific object of the invention is to provide a catheter capable of delivering an aerated stream of liquid to a body cavity wherein the tendency of the bubbles to coalesce and/or dissolve before reaching the region to be visualized is substantially reduced.